Swells up, being first after daughter finishes (8)
I believe the answer is:
distends
'swells' is the definition.
('distend' can be a synonym of 'swell')
'up being first after daughter finishes' is the wordplay.
'up being first' becomes 'ist' (I am not sure about this - if you are sure you should believe this answer much more).
'after' says to put letters next to each other.
'daughter' becomes 'd'.
'finishes' becomes 'ends' ('end' can be a synonym of 'finish').
'ist' after 'd' is 'dist'.
'dist'+'ends'='DISTENDS'
Can you help me to learn more?
(Other definitions for distends that I've seen before include "Expands, dilates" , "bulges" , "stretches out" , "Swells by pressure from within" , "Becomes wider" .)